N-substituted tetrahydroquinolines for use as antioxidants in lubricants

ABSTRACT

Composition containing (a) at least one lubricant, hydraulic oil or metal-working fluid based on mineral oil or synthetic oils and (b) 0.05-5% by weight, based on the total weight of the lubricant, hydraulic oil or metal-working fluid composition, of at least one compound of the formula I, ##STR1## where R 1  and R 2  are independently alkyl, aryl, substituted aryl or benzyl, R 3  is hydrogen or methyl, R 4  and R 5  are independently hydrogen, methyl, methoxy, chloro or nitro, R 6  is alkyl, alkenyl, aralkyl or substituted benzyl, and R 13  is hydrogen or methyl.

This is a divisional of application Ser. No. 135,964, filed on Dec. 21, 1987, now U.S. Pat. No. 4,828,741, issued on May 9, 1989.

The present invention relates to lubricant, hydraulic oil or metal-working fluid compositions containing as stabilizers N-substituted 1,2,3,4-tetrahydroquinolines, to novel N-substituted 1,2,3,4-tetrahydroquinolines, and to the use of such N-substituted 1,2,3,4-tetrahydroquinolines as stabilizers in lubricants, hydraulic oils and metal-working fluids.

In general, various additives are added to mineral and synthetic lubricants, hydraulic oils or metal-working fluids to improve their performance characteristics. In particular there is a demand for additives which actively inhibit the oxidation or ageing of the lubricant, hydraulic oil or metal-working fluid and thus extend their life.

EP-A-72,349 discloses N-unsubstituted 1,2,3,4-tetrahydroquinolines for use as antioxidants in lubricants. DE-A-2,156,371 describes N-substituted 1,2,3,4-tetrahydroquinoline derivatives for use as stabilizers in colour former compositions for pressure-sensitive recordings. Furthermore, 1-amino-or 1-hydroxyalkyl-1,2,3,4-tetrahydroquinolines are described in US-A-3,247,211 as starting materials for dyes. Moreover, US-A-2,846,435 discloses N-alkyl-1,2,3,4-tetrahydroquinolines for use as rubber stabilizers, and GB-A-795,497 discloses N-substituted 1,2,3,4-tetrahydroquinolines for use as flexibility improvers for polymeric polyolefin coatings on metals.

The present invention accordingly provides a composition containing

(a) at least one lubricant, hydraulic oil or metal-working fluid based on mineral oil or synthetic oils and

(b) 0.05-5% by weight, based on the total weight of the lubricant, hydraulic oil or metal-working fluid composition, of at least one compound of the formulae I, II or/and V ##STR2## in which R¹ and R² are independently of each other C₁ -C₈ -alkyl, unsubstituted or C₁ -C₁₂ -alkyl-, Cl-, Br-, I-, NO₂ -, OH- or C₁ -C₁₂ -alkoxy-substituted phenyl or naphthyl, or benzyl, R³ is hydrogen or methyl, R⁴ and R⁵ are independently of each other hydrogen, methyl, methoxy, -Cl or -NO₂ and R⁴ additionally in the formula I is a radical of the formula III ##STR3## in which R¹⁵ and R¹⁶ are independently of each other hydrogen, C₁ -C₉ -alkyl, unsubstituted or C₁ -C₁₂ -alkyl-substituted phenyl, or benzyl, α-methylbenzyl or α,α-dimethylbenzyl, or R¹⁵ and R¹⁶ are together with the C atom to which they are bonded a 5-, 6- or 7-ring, with the proviso that when R⁴ is a radical of the formula III R⁵ is hydrogen, and in which furthermore R⁶ is C₁ -C₁₈ -alkyl, C₃ -C₁₈ -alkenyl, C₇ -C₁₂ aralkyl, C₇ -C₁₂ -alkaryl or C₁ -C₁₂ -alkyl-, Cl-, Br-, I-, NO₂ -, OH- or C₁ -C₁₂ -alkoxy-ringsubstituted benzyl, R⁷ is hydrogen or methyl, R⁸, if n is 1, is hydrogen, CH₂ OR¹⁴, C₁ -C₁₈ -alkyl, phenyl or -CH₂ SR¹⁴ or, if n is 2 to 4, a radical of the formulae ##STR4## and in which furthermore R⁹ is hydrogen, methyl, ##STR5## or R¹⁰, R¹² and R¹³ are independently of one another hydrogen or methyl, R¹¹ is hydrogen, methyl or ethyl and R¹⁴ is C₁ -C₁₈ -alkyl, C₇ -C₁₃ -alkaryl, phenyl, naphthyl, pentalyl, heptalyl, indacyl or unsubstituted or C₁ -C₁₂ -alkyl-, Cl-, Br-, I-, NO₂ -, OH- or C₁ -C-₁₂ -alkoxyringsubstituted benzyl, n is a number from 1 to 4, m and q are numbers from 1 to 10, p is a number from 2 to 10, and R¹⁷ is either C_(x) H_(2x), where x is 0 to 10, or --CH═CH--.

A C₁ -C₈ -alkyl R¹ or R² is a straight-chain or branched alkyl radical, for example methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec.-butyl, tert.-butyl, straight-chain or branched pentyl, hexyl, heptyl or octyl.

A C₁ -C₉ -alkyl R¹⁵ or R¹⁶ is a straight-chain or branched alkyl radical, for example methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec.-butyl, tert.-butyl, straight-chain or branched pentyl, hexyl, heptyl, octyl or nonyl.

A C₁ -C₁₈ -alkyl R⁶, R⁸ or R¹⁴ is a straight-chain or branched alkyl radical, for example methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec.-butyl, tert.-butyl, straight-chain or branched pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl or octadecyl. R⁸ is preferably C₁ -C₁₂ -alkyl.

A C₃ -C₁₈ -alkenyl R⁶ is a straight-chain or branched alkenyl radical which contains one or more, but preferably one double bond, for example allyl, n-butenyl, 1,3-butadieyl, i-pentenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, undecenyl, dodecenyl, tridecenyl, 2-nonyl-2-butenyl, tetradecenyl, pentadecenyl, hexadecenyl, 8-heptadecenyl, 2-octadecenyl or oleyl. Preference is given to allyl or oleyl, in particular allyl.

In a C₁ -C₁₂ -alkyl-substituted phenyl R¹, R², R¹⁵ or R¹⁶ and a C₁ -C₁₂ -alkyl-ringsubstituted benzyl R⁶ or R¹⁴, the phenyl or benzyl radical can be monosubstituted or polysubstituted, preferably monosubstituted or disubstituted, in the case of R¹⁵ and R¹⁶, however, only monosubstituted. C₁ -C₁₂ -Alkyl is for example methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec.-butyl, tert.-butyl, straightchain or branched nonyl or dodecyl.

In a C₁ -C₁₂ -alkoxy-substituted phenyl R¹ or R² and a C₁ -C₁₂ -alkoxy-ringsubstituted benzyl R⁶ or R¹⁴, the phenyl or benzyl radical can be monosubstituted or polysubstituted, but preferably monosubstituted or disubstituted; C₁ -C₁₂ -alkoxy is, for example, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec.-butoxy, tert.-butoxy, straight-chain or branched nonyloxy or dodecyloxy.

A C₇ -C₁₂ -aralkyl R⁶, preferably phenyl-C₁ -C₄ -alkyl, is, for example, benzyl, 1- or 2-phenethyl, 3-phenyl-propyl, α,α-dimethylbenzyl, 2-phenylisopropyl, 2-phenylhexyl or naphthylmethyl. Preference is given to benzyl and α,α-dimethylbenzyl, in particular benzyl.

In a C₇ -C₁₂ -alkaryl R⁶ and a C₇ -C₁₃ -alkaryl R¹⁴, the aryl radical is phenyl or naphthyl, but preferably phenyl, which are each monosubstituted or polysubstituted, preferably monosubstituted or disubstituted, by C₁ -C₆ -alkyl and C₁ -C₇ -alkyl respectively, preferably by C₁ -C₄ -alkyl, e.g. 2,4,6trimethylphenyl, 2,4-dimethylphenyl, 4-isopropylphenyl, 4hexylphenyl, 4-methylphenyl, 3,4-diethylphenyl, 2-methylnaphthyl or 2,6-dimethylnaphthyl. However, preference is given to 2,5-dimethylphenyl and 4-methylphenyl, in particular 4methylphenyl.

Preference is given to a composition containing as component (b) at least one compound of the formulae I or/and II in which R¹ and R² are independently of each other C₁ -C₈ -alkyl or benzyl, particularly preferably C₁ -C₈ -alkyl, very especially preferably C₁ -C₄ -alkyl, in particular methyl or ethyl.

Preference is likewise given to a composition containing as component (b) at least one compound of the formulae I or/and II in which R³ is hydrogen.

Also of interest is a composition containing as component (b) at least one compound of the formulae I or/and II in which R⁴ and R⁵ are independently of each other hydrogen or methyl.

Of particular interest is a composition containing as component (b) at least one compound of the formula I in which R⁴ is a radical of the formula III ##STR6##

Of similar interest is a composition containing as component (b) at least one compound of the formula I in which R⁶ is C₁ -C₁₂ -alkyl, C₃ -C₈ -alkenyl or benzyl, but preferably C₁ -C₄ -alkyl, allyl, methallyl or benzyl.

Also of interest is a composition containing as component (b) at least one compound of the formula II in which R⁷ is hydrogen.

A further embodiment is a composition containing as component (b) at least one compound of the formula II in which R⁸ is hydrogen, C₁ -C₄ -alkyl, phenyl, --CH₂ O--(CH₂)p--OCH₂, --CH₂ O--(CH₂ --CH₂ --, --(CH₂)_(m) --, ##STR7## but preferably hydrogen or methyl, and n is 1 or 2.

A specific embodiment is a composition containing as component (b) at least one compound of the formula II in which R⁹ is hydrogen, methyl, ##STR8## but preferably hydrogen.

A similarly interesting embodiment is a composition containing as component (b) at least one compound of the formulae I or/and II in which R¹³ is methyl.

A particular embodiment is a composition containing as component (b) at least one compound of the formula II in which n is 1 or 2.

An additional embodiment is a composition containing as component (b) at least one compound of the formula II in which m, p and q are independently of one another a number from 2 to 6.

The present invention further provides the novel compounds N-(2-hydroxypropyl)-2,2,4,7-tetramethyl-1,2,3,4-tetrahydroquinoline, N-[2-hydroxy-3-(tert.-nonylthio)-propyl]-2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline, tert.-nonylthio)-propyl]-2,2,4,6-tetramethyl-1,2,3,4-tetrahydroquinoline.

The present invention likewise provides the novel compounds of the formula IV ##STR9## in which R¹ and R² are independently of each other C₁ -C₈ -alkyl, unsubstituted or C₁ -C₁₂ -alkyl, Cl-,Br-, I-, NO₂ -, OH- or C₁ -C₁₂ -alkoxy-substituted phenyl or naphthyl, or benzyl, R³ is hydrogen or methyl, R⁶ is C₁ -C₁₈ -alkyl, C₃ -C₈ -alkenyl, C₇ -C₁₂ -aralkyl, C₇ -C₁₂ -alkaryl or C₁ -C₁₂ -alkyl-, Cl-, Br-, I-, NO₂ -, OH- or C₁ -C₁₂ -alkoxy-ring-substituted benzyl, R¹³ is hydrogen or methyl, R¹⁵ and R¹⁶ are independently of each other hydrogen, C₁ -C₉ -alkyl, unsubstituted or C₁ -C₁₂ -alkyl-substituted phenyl, benzyl, α-methylbenzyl or α,α-dimethylbenzyl, or in which R¹⁵ and R¹⁶ together with the C atom to which they are bonded are a 5-, 6- or 7-ring.

Specific preference is given to the compounds of the formula IV in which R¹⁵ and R¹⁶ together with the C atom to which they are bonded are a 5-, 6- or 7-ring, or R¹⁵ and R¹⁶ are independently of each other hydrogen or C₁ -C4-alkyl.

Examples of compounds of the formulae I and II are: 1,2,2,4-tetramethyl-1,2,3,4-tetrahydroquinoline, 1-ethyl-2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline, 1,2-dimethyl-2,4-diethyl-1,2,3,4-tetrahydroquinoline, 2-methyl-1,2,4-triethyl-1,2,3,4-tetrahydroquinoline, 1-benzyl-2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline, 1-allyl-2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline, 1-benzyl-2,2,4,6,7-pentamethyl-1,2,3,4-tetrahydroquinoline, 1-butyl-2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline, 1-(2-hydroxyethyl)-2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline, 1-(2-hydrxypropyl)-2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline, 1-(2-acetoxypropyl)-2,2,4,6-tetramethyl-1,2,3,4-tetrahydroquinoline, 1-(2-hydroxyethyl)-2,2,4,6-tetra-methyl-1,2,3,4-tetrahydroquinoline, 1-(2-hydroxyethyl)-2,4-diethyl-2-methyl-1,2,3,4-tetrahydroquinoline, 1-(2-hydroxy-ethyl)-2,2,4,7-tetramethyl-1,2,3,4-tetrahydroquinoline, 1-(2-hydroxypropyl)-2,4diethyl-2methyl-1,2,3,4-tetrahydroquino-line, 1-(2-acetoxyethyl)-2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline, 1-(β-methallyl)-2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline, 1,16-bis-[2,2,4-trimethyl-1,2,3,4-tetrahydroquinol-1-yl]-2, 15-dihydroxy-4,13-dioxa-hexadecane, 1,16-bis-]2,2,4-trimethyl-1,2,3,4-tetrahydroquinol-1-yl]-2, 15-dihydroxy-4,7,10,13-tetraoxa-hexadecane, 1,14-bis-[2,2,4-trimethyl-1,2,3,4-tetrahydroquinol-1yl]-2, 13-dihydroxy-4,11-dioxatetradecane, 1,13-bis-[2,2,4-trimethyl-1,2,3,4-tetrahydro-quinol-1yl[-2, 12-dihydroxy-4,7,10-trioxa-tridecane, 1,10-bis-[2,4-diethyl-2-methyl-1,2,3,4-tetrahydroquinol-1-yl]-2,9-dihydroxy-4,7-dioxa-decane,2,2-di-{4-[3'-(2,2,4-trimethyl-1,2,3,4-tetrahydroquinol-1-yl)-2'-hydroxy-prop-1'-oxy]-phenyl}-propane, 1,1-di-{4-[3'-(2,2,4,6-tetramethyl-1,2,3,4tetra-hydroquinol-1-yl)-2'-hydroxy-prop-1'-oxy]-phenyl}-methane, 1-[2,2,4-trimethyl-1,2,3,4-tetrahydroquinol-1-yl]-3-(tert.-octylthio)-propan-2-ol, 1-[2,2,4-trimethyl-1,2,3,4-tetrahydro-quinol-1-yl]-3-(p-tolyloxy)-propan-2-ol, 1-[ 2,2,4-trimethyl-1,2,3,4-tetrahydroquinol-1-yl)-3-(o-tolyloxy)-propan-2-ol, 1-(4-butylphenyl)-2,4-diethyl-6,7-dimethoxy-2-methyl-1,2,3,4-tetrahydroquinoline, 1-(oleyl)-2,4-diphenyl-4-methyl-1,2,3,4-tetrahydroquinoline, 1-(3-methoxy-pentadec-2-yl)-4-benzyl-6,7-dichloro-2,4-dimethyl-1,2,3,4-tetrahydroquinoline, 1,1-bis-[1-(3',5'-dimethyl-phenyl)-2,2,4-trimethyl-1,2,3,4-tetra-hydroquinol-6-yl]-methane, 1,1-bis-[1-(2'-hydroxyethyl)-2,4-diethyl-2-methyl-1,2,3,4-tetrahydroquinol-6-yl]-methane, 1,1-bis-[1,2-diethyl-2,4-dimethyl-1,2,3,4-tetrahydroquinol-6-yl]-cyclohexane.

The preparation of the compounds of the formulae I and II is effected in a conventional manner.

For instance, aniline and a methyl ketone can be reacted in a molar ratio of 1:2 as described in Org. Synthesis, Coll. Vol. III, p. 329-32, or in US-A-2,846,435. The resulting N-unsubstituted 1,2,3,4-tetrahydroquinoline can be reacted in a conventional manner with customary alkylating, arylating or benzylating agents, e.g. dimethyl sulfate, allyl bromide, iodobenzene or benzyl chloride, to the compounds of the formula I.

The compounds of the formula II can be prepared as described in US-A-3,247,211.

Novel compounds of the formula I or II can be prepared in a similar manner.

The compounds according to the invention of the formulae I, II and IV are very highly suitable for use as antioxidants in lubricants, hydraulic oils and metal-working fluids, in particular in lubricants and hydraulic oils, especially in lubricants.

The present invention therefore also provides a method of using the compounds of the formula I, II and IV as antioxidants in lubricants, hydraulic oils or metal-working fluids.

The compounds of the formulae I and II are sufficiently soluble in lubricants, hydraulic oils and metal-working fluids and are preferably added to these substrates in an amount of 0.1-2.5% by weight, based on the total weight of the lubricant, hydraulic oil or metal-working fluid composition.

These lubricant, hydraulic oil or metal-working fluid systems can be polar or apolar. The selection criteria are based on the solubility properties of the corresponding compounds. The lubricants, hydraulic fluids and metal-working fluids which come into consideration are known to those skilled in the art and are described for example in "Schmiermittel Taschenbuch" (Huthig Verlag, Heidelberg, 1974), in "Ullmanns Encyclopadie der technischen Chemie", volume 13, pages 85-94 (Verlag Chemie, Weinheim, 1977) and D. Klamann "Schmierstoffe und verwandte Produkte" pages 158-174 (Verlag Chemie, Weinheim, 1982) respectively.

Particularly suitable are in addition to mineral oils for example poly-α-olefins, ester lubricants, phosphate, glycols, polyglycols and polyalkylene glycols and mixtures thereof with water.

The lubricants, hydraulic fluids and metal-working fluids can additionally contain other additives which are added to further improve the basic properties of these substances; they include: further antioxidants, metal passivators, rust inhibitors, viscosity index improvers, setting point reducers, dispersants, detergents and also high pressure additives and antiwear additives.

EXAMPLES OF PHENOLIC ANTIOXIDANTS

1. Alkylated monophenols 2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butylphenol, 2,6-Di-tert-butyl-4-methylphenol, 2,6-di-tert-butylphenol, 2-tert-butyl-4,6-dimethylphenol, 2,6-di-tert-butyl-4-ethyl-phenol, 2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butyl-4-n-butylphenol, 2,6-di-tert-butyl-4-iso-butylphenol, 2,6-di-cyclopentyl-4-methylphenol, 2-(α-methylcyclohexyl)-4,6-dimethylphenol, 2,6-di-octadecyl-4-methylphenol, 2,4,6-tricyclohexylphenol, 2,6-di-tert-butyl-4-methoxymethylphenol, o-tert-butylphenol.

2. Alkylated hydroquinones 2,6-Di-tert-butyl-4-methoxyphenol, 2,5-di-tert-butyl-hydroquinone, 2,6-diphenyl-4-octadecyloxyphenol

3. Hydroxylated thiodiphenyl ethers 2,2'-thio-bis-(6-tert-butyl-4-methylphenol), 2,2'-thio-bis-(4-octylphenol), 4,4'-thio-bis-(6-tert-butyl-3-methylphenol), 4,4'-thio-bis-(6-tert-butyl-2-methylphenol).

4. Alkylidenebisphenols 2,2'-Methylene-bis-(6-tert-buty-4-methylphenol), 2,2'-methylene-bis-(6-tert-butyl-4-ethylphenol), 2,2'-methylene-bis-[4-methyl-6-(α-methylcyclohexyl)-phenol], 2,2'-methylene-bis-(4-methyl-6cyclohexylphenol), 2,2'-methylene-bis-(6-nonyl-4-methylphenol), 2,2'-methylene-bis-(4,6-di-tert-butylphenol), 2,2'-ethylidene-bis-(4,6-di-tert-butylphenol), 2,2'-ethylidene-bis-(6-tert-butyl-4-iso-butylphenol), 2,2'-methylene-bis-[6-(α, α-dimethylbenzyl)-4-nonylphenol], 4,4'-methylene-bis-(2,6-di-tert-butylphenol), 4,4'-methylene-bis-(6-tert-butyl-2-methylphenol), 1,1-bis-(5-tert-butyl-4-hydroxy-2-methylphenyl)butane, 2,6-di-(3-tert-butyl-5-methyl-2-hydroxybenzyl)-4methylphenol, 1,1,3-tris-(5-tert-butyl-4-hydroxy-2-methylphenyl)-3-n-dodecylmercaptobutane, ethylene glycol bis-[3,3-bis-(3'-tert-butyl-4'-hydroxyphenyl) butyrate], di-(3-tert-butyl-4-hydroxy-5methylphenyl)-dicyclopentadiene, di-[2-(3'-tert-butyl-2'-hydroxy-5'-methyl-benzyl)-6tert-butyl-4-methyl-phenyl] terephthalate.

5. Benzyl compounds1,3,5-Tri-(3,5-di-tert-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene, di-(3,5-di-tert-butyl-4-hydroxybenzyl) sulfide, isooctyl 3,5-di-tert-butyl-4-hydroxybenzyl-mercaptoacetate, bis-(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)-dithiol terephthalate, 1,3,5-tris-(3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate, 1,3,5-tris-(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl) isocyanurate, dioctadecyl 3,5-di-tert-butyl-4-hydroxybenzyl-phosphonate, calcium salt of monoethyl 3,5-di-tert-butyl-4-hydroxybenzyl-phosphonate. 6. Acylaminophenols4-Hydroxylauranilide, 4-hydroxystearanilide, 2,4-bis-octylmercapto-6(3, 5-di-tert-butyl-4-hydroxyanilino)-s-triazine, octyl N-(3,5-di-tert-butyl-4-hydroxyphenyl)-carbamate. 7. Esters of β-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic acid with monohydric or polyhydric alcohols, for example with

    ______________________________________                                         methanol        diethylene glycol                                              octadecanol     triethylene glycol                                             1,6-hexanediol  pentaerythritol                                                neopentyl glycol                                                                               tris-hydroxyethyl isocyanurate                                 thiodiethylene glycol                                                                          dihydroxyethyloxamide                                          ______________________________________                                          8. Esters of β-(5-tert-butyl-4-hydroxy-3-methylphenyl)-propionic acid      with monohydric or polyhydric alcohols, for example with

    ______________________________________                                         methanol        diethylene glycol                                              octadecanol     triethylene glycol                                             1,6-hexanediol  pentaerythritol                                                neopentyl glycol                                                                               tris-hydroxyethyl isocyanurate                                 thiodiethylene glycol                                                                          dihydroxyethyloxamide                                          ______________________________________                                          9. Amides of β-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionic acid for      example      N,N'-di-(3,5-di-tert-butyl-4-hydroxyphenyl-propionyl)-hexamethylenediamine     , N,N'-di-(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)-trimethylenediamine,      N,N-di-(3,5-di-tert-butyl-4-hydroxyphenylpropionyl)-hydrazine.

EXAMPLES OF AMINE ANTIOXIDANTS

N,N'-Di-isopropyl-p-phenylenediamine, N,N'-di-sec-butyl-pphenylenediamine, N,N'-bis(1,4-dimethyl-pentyl)-p-phenylenediamine, N,N'-bis(1-ethyl-3-methyl-pentyl)-p-phenylenediamine, N,N'-bis(1-methyl-heptyl)-p-phenylenediamine, N,N'-diphenyl-p-phenylenediamine, N,N'-di-(naphthyl-2)-p-phenylenediamine, N-isopropyl-N'-phenyl-p-phenylenediamine, N-(1,3-dimethyl-butyl)-N'-phenyl-p-phenylenediamine, N-(1-methyl-heptyl)-N'-phenyl-p-phenylenediamine, N-cyclohexyl-N'-phenyl-p-phenylenediamine, 4-(p-toluene-sulfonamido)-diphenylamine, N,N'-di-methyl-N,N'-di-sec-butyl-p-phenylenediamine, diphenylamine, 4-isopropoxy-diphenylamine, N-phenyl-1-naphthylamine, N-phenyl-2naphthylamine, octylated diphenylamine, 4-n-butylaminophenol, 4-butyrylamino-phenol, 4-nonanoylamino-phenol, 4-dodecanoylamino-phenol, 4-octadecanoylamino-phenol, di-(4-methoxy-phenyl)-amine, 2,6-di-tert-butyl-4-dimethylamino-methyl-phenol, 2,4'-diamino-diphenylmethane, 4,4'-diamino-diphenylmethane, N,N,N',N'-tetramethyl-4,4'-diamino-diphenylmethane, 1,2-di[(2-methyl-phenyl)-amino]-ethane, 1,2-di-(phenylamino)-propane, (o-tolyl)-biguanide, di-[4-(1',3'-di-methyl-butyl)-phenyl) amine, tert-octylated N-phenyl-1-naphthylamine, mixture of monoalkylated and dialkylated tert-butyl-/tert-octyldiphenylamines.

EXAMPLES OF METAL PASSIVATORS ARE

For copper, for example: triazole, benzotriazole and derivatives thereof, 2-mercaptobenzothiazole, 2,5-dimercaptothiadiazole, salicylidenepropylenediamine, salts of salicylaminoguanidine.

EXAMPLES OF RUST INHIBITORS ARE

(a) organic acids, their esters, metal salts and anhydrides, for example: N-oleoyl-sarcosine, sorbitan monooleate, lead naphthenate, dodecenylsuccinic anhydride, monoalkenyl succinates, 4-nonylphenoxyacetic acid.

(b) nitrogen-containing compounds, for example: I. primary, secondary or tertiary aliphatic or cycloaliphatic amines and amine salts of organic and inorganic acids, for example oil-soluble alkylammonium carboxylates.

II. heterocyclic compounds, for example: substituted imidazolines and oxazolines.

(c) Phosphorus-containing compounds, for example: amine salts of partial phosphoric esters.

(d) Sulfur-containing compounds, for example: barium dinonylnaphthalenesulfonate, calcium petroleumsulfonates.

EXAMPLES OF VISCOSITY INDEX IMPROVERS ARE FOR EXAMPLE

polymethacrylates, vinylpyrrolidone/methacrylate copolymers, polybutenes, olefin copolymers, styrene/acrylate copolymers.

EXAMPLES OF SETTING POINT REDUCERS ARE FOR EXAMPLE

polymethacrylate, alkylated naphthalene derivatives.

EXAMPLES OF DISPERSANTS/SURFACTANTS ARE, FOR EXAMPLE

Polybutenylsuccinimides, polybutenylphosphonic acid derivatives, basic magnesium, calcium ad barium sulfonates and phenolates.

EXAMPLES OF ANTIWEAR ADDITIVES ARE FOR EXAMPLE

Sulfur- and/or phosphorus- and/or halogen-containing compounds, such as sulfurized vegetable oils, zinc dialkyl dithiophosphates, tritolyl phosphate, chlorinated paraffins, alkyl and aryl disulfides.

EXAMPLE 1

350 g of 2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline, 2000 ml of ethanol and 110 g of ethylene oxide are heated at 180° C. in an autoclave for 12 hours. The ethanol is then distilled off, and the crystals of 1-(2-hydroxyethyl)-2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline are filtered off. Recrystallization from ethanol gives a product having a melting point of 73°-75° C.

The method of Example 1 is repeated to prepare Examples 2-6.

EXAMPLE 7

52.6 g of 2,2,4-trimethyl-1,2,3,4-tetrahydroquinoline and 37.2 g of dimethyl methanephosphonate are heated together for 5 hours at 160° C. in a slow stream of nitrogen. Thereafter the reaction mixture is cooled down to 60° C. and taken up in 100 ml of toluene, and the mixture is brought to an alkaline pH with 130 g of 10% NaOH solution. The organic phase is separated off, washed twice with 100 ml of water each time and evaporated at 80° C. in a rotary evaporator. The residue is then dried at 60° C. in a high vacuum. 54.1 g are obtained of a clear, light brown oil having a boiling point of 274° C. at 1013 mbar.

Examples 8 to 11 are obtained in a similar manner.

EXAMPLE 12

35.1 g of 12,2,4-trimethyl-1,2,3,4-tetrahydroquinoline are introduced into a flask and heated to 90° C., and 47.6 g of tert.-nonyl glycidyl thioether are added dropwise with stirring. After everything has been added, the mixture is stirred at 90° C. for a further 0.5 hour. An oil having a boiling point of 185° C. at 0.03 mbar is obtained.

Example 13 is prepared in a similar manner.

                                      TABLE 1                                      __________________________________________________________________________     Example number                                                                          Compound                  Melting/boiling point                       __________________________________________________________________________               ##STR10##                 73-75° C.                           2                                                                                        ##STR11##                110-112° C./0.4 mbar                 3                                                                                        ##STR12##                130-134° C./0.53 mbar                4                                                                                        ##STR13##                 78-79° C.                           5                                                                                        ##STR14##                120° C./0.2 mbar                     6                                                                                        ##STR15##                130-135° C./0.13 mbar                7                                                                                        ##STR16##                274° C./1013 mbar                    8                                                                                        ##STR17##                 84-86° C./0.2 mbar                  9                                                                                        ##STR18##                283° C./1013 mbar                    10                                                                                       ##STR19##                105° C./0.27 mbar                    11                                                                                       ##STR20##                296° C./1013 mbar                    12                                                                                       ##STR21##                185° C./0.03 mbar                    13                                                                                       ##STR22##                194° C./0.03 mbar                    __________________________________________________________________________       Example 14:

THIN-FILM OXYGEN UPTAKE TEST (TFOUT)

This test is a modified version of the "rotary bomb oxidation test for mineral oils" (ASTM D 2272). It is described in detail in "C.S. Ku and S.M. Hsu, A Thin-Film Oxygen Uptake Test for the Evaluation of Automotive Crankcase Lubricants, Lubrication Engineering, vol. 40 (2), 75-83 (1984)". The test oil used is a motor oil which is based on mineral oil and contains half the customary amount of zinc dithiophosphate (0.75%; zinc content 0.06%, based on the motor oil).

The compound prepared is tested in the motor oil described in the presence of 2% of water, in the presence of a liquid oxidized nitrated fraction of a motor petrol as catalyst (4% starting concentration) and in the presence of a liquid metal naphthenate as further catalyst (4% starting concentration). The water and the two liquid catalyst substances are supplied by the National Bureau of Standards (NBS) as No. Standard Reference Material 1817 together with a certificate of analysis. The test terminates with an appreciable break in the pressure/time diagram. The results indicated in Table 2 signify the time (in minutes) to the break in the pressure-time diagram.

Long times correspond to high stabilizer activity. Concentration of stabilizer: 0.5% by weight, based on the oil.

                  TABLE 2                                                          ______________________________________                                         Stabilizer Minutes to appreciable pressure loss                                ______________________________________                                         none        76                                                                 Example 1  199                                                                 Example 3  185                                                                 Example 4  197                                                                 Example 6  186                                                                 Example 7  220                                                                 Example 8  218                                                                 Example 9  200                                                                 ______________________________________                                     

What is claimed is:
 1. A process for stabilizing a lubricant, hydraulic oil or metal-working fluid against oxidative degradation which comprisesincorporating into said lubricant, hydraulic oil or metal-working fluid 0.05-5% by weight, based on the total weight of lubricant, hydraulic oil or metal-working fluid composition, of at least one compound of formula I ##STR23## in which R¹ and R² are independently of each other C₁ -C₈ alkyl, unsubstituted or C₁ -C₁₂ -alkyl-, Cl-, Br-, NO₂ -, OH- or C₁ -C₁₂ -alkoxy substituted phenyl or naphthyl, or benzyl, R³ is hydrogen or methyl, R⁴ and R⁵ are independently of each other hydrogen, methyl, methoxy, -Cl or -NO₂, and R⁴ additionally in formula I is a radical of formula III ##STR24## in which R¹⁵ and R¹⁶ are independently of each other hydrogen, C₁ -C₉ -alkyl, unsubstituted or C₁ -C₁₂ alkyl-substituted phenyl, or benzyl, α-methylbenzyl, α,α-dimethylbenzyl, or R¹⁵ and R¹⁶ are, together with the C atom to which they are bonded, a 5-, 6- or 7-membered ring, with the proviso that when R⁴ is a radical of formula III, R⁵ is hydrogen, and in which furthermore R⁶ is C₁ -C₁₈ -alkyl, C₃ -C₁₈ -alkenyl, C₇ -C₁₂ -aralkyl, C₇ -C₁₂ alkaryl or C₁ -C₁₂ -alkyl, Cl-, Br-, Br-, I-, NO₂ -, OH- or C₁ -C₁₂ -alkoxy-ring substituted benzyl, and R¹³ is hydrogen or methyl.
 2. A process according to claim 1 where in the compounds of formula I, R¹ or R² are independently of each other C₁ -C₄ -alkyl.
 3. A process according to claim 2 where in R¹ or R² are independently of each other methyl or ethyl.
 4. A process according to claim 1 where in the compounds of formula I, R³ is hydrogen.
 5. A process according to claim 1 where in the compounds of formula I, R⁴ or R⁵ are independently of each other hydrogen or methyl.
 6. A process according to claim 11 where in the compounds of formula I, R⁴ is a radical of formula III.
 7. A process according to claim 1 where in the compounds of formula I, R⁶ is C₁ -C₁₂ -alkyl, C₃ -C₈ -alkenyl or benzyl.
 8. A process according to claim 7 wherein R⁶ is C₁ -C₄ -alkyl, allyl, methallyl or benzyl.
 9. A process according to claim 1 where in the compounds of formula I, R² is methyl, R³ is hydrogen, R¹ and R¹³ are methyl, R⁴ and R⁵ are hydrogen and R⁶ is methyl, allyl or benzyl.
 10. A process according to claim 11 where in the compounds of formula I, R¹³ is methyl.
 11. A process according to claim 11 for stabilizing a lubricant or a hydraulic oil.
 12. A process according to claim 11 wherein the compound of formula I is 1,2,2,4-tetramethyl-1,2,3,4-tetrahydroquinoline. 